Valve gear for reversible reciprocating fluid pressure engines, especially for locomotives



May-21, 1940. H LENTZ 2,201,907

VALVE GEARFOR REVERSIBLE RECIPROCATING FLUID PRESSURE ENGINES, ESPECIALLY FOR LOCOMOTIVES Filed Feb. 23, 1938 4 Sheets-Sheet 1 In i/enzan:

May 21, 1940. H j LEN-r2 2,201,907

VALVE GEAR FOR REVERSIBLE RECIPROCATING FLUID PRESSURE ENGINES, ESPECIALLY FOR LOCOMOTIVES Filed Feb. 25, 1938 4 Sheets-Sheet 2 y mm In vnzop:

4 Sheets-Sheet 3 J. LENTZ ESPECIALLY FOR LOCOMOTIVES Filed Feb. 23, 1938 Inventor:

May 21, 1940.

VALVE GEAR FOR REVERSIBLE RECIPROCATING FLUID PRESSURE ENGINES Fjgtfl H. J. LENTZ May 21, 1940.

URE

VALVE GEAR FOR REVERSIBLE RECIPROCATING FLUID PRESS ENGINES, ESPECIALLY FOR LOCOMOTIVES 4 Sheets-Sheet 4 Filed Feb. 23, 1938 controlled by an exhaust cam which at the re- Patented May 21, 1940 VALVE GEAR FOR REVERSIBLE RECIPE)- CATING FLUID PRESSURE ENGINES; ESPE- CIALLY FOR LOCOMOTIVES I Hugo JohannesLentz, Vienna, Austria Application February 23, 1938, Serial No.'192,'1 21 In Great Britain August 7, 1937 oiai s. (01. 121-127) This invention relates to a valve gear for reversible reciprocating fluid pressure engines,

especially for locomotives in which the valves are actuated by rotating cams, especially inwhich for controlling the steam admission two' relatively adjustable cams are used of which, in one direc- -tion of rotation, one cam determines the begin-,

ning of the admission lead and the other the end of the cut-off, whereas in the other direction of rotation the functions of the camsare reversed. The steam exhaust from the cylinder is mostly versal is swung through a corresponding angle range and which determines both the beginning of the exhaust lead and also the beginning of the compression.

The known gears of this type are all open to the objection that the control points which determine the beginning of the admission lead and the beginning of the compression are interdependent through the gear drive and consequent- 15 cannot be independently adjusted to assume the most favourable position for the steam distribution and steam utilization at the cut-offactually adjusted. This is not attained by the gears hitherto known, because all the cams are adjusted through an angle corresponding to the changeof cut-off 'or not at all or the gear drive. 1

The present invention is based on the idea of arranging the cam shaft shiftable relatively to all the cams and to adjust each cam separately by control grooves in the periphery of the cam by the reversal shaft and catches engaging in and guided by these grooves, so that, corresponding to the different pitches of the control grooves the individual cams are adjusted through diiferentangles which are independent of one another. It is therefore possible to makethe grooves or groove sections controlling the individual cams of a shape and pitch which ensure the most favourable position of the control points and therefore.

the best steam utilization for the type of engine in question,

The control grooves may be arranged with different pitches in helical shape on the periphery of the cam shat t; but, if necessary, parts of the grooves may extend axially if an adjustment of the cams is not to take place.

This construction of the gear enables accurate adaptation to the service conditions, in using an extremely simple mechanical control drive.

The invention also relates to a special construction of theintermediate members cooperating with the control cams and acting on the conthe admission valve and at the'left of the control 10 .shaft in the direction of the exhaust valve spindle.-

Fig. 2 shows a Fig. 1.

Fig. 3 shows in elevation the intermediate lever arranged between admission control cam and admission valve spindle viewed in the direction of the arrow B of Fig. 1.

Fig. 4 shows a portion of the circumference of the cam shaft of the control grooves, developed to a plane. 2

' Figs. 5 to 7 show each a different position of the control cams,

Fig. 8 shows a second form of construction of the control cams which are arranged on the cam shaft so'that this shaft need have only one single continuous control groove.

Figs. 9a to 9d show the control "grooves according to the cam arrangement of Fig; 8 developed to a plane in the different positions for maximum and minimum cut-off forward and backward.

Fig. 10 is a longitudinal section through a control chest for valves arranged hanging in the cross section'on line 11-11 of cylinder.

of Fig. 12 and Fig. 14 a cross section on line XIV XIV'of Fig. 12.

On the 'cylinder I a control chest 2 is mounted in which the steam channels for the admission and discharging of the steam and the control valves are accommodated; The cam shaft l5 with the admission and exhaust control cams mounted thereon is arranged in the middle of the control chest and transversely to the same. On each side of the cam shaft an admission valve 3 and anexhaust valve 4 are arranged in" the control chest, the spindles I3 or I4 of said valves being parallel to one another and directed towards the :cam shaft. In Fig. 1 a section in the direction of the spindle of the admission valve is shown at the right of the cam shaft and at the left of the same a section in the direction ofthe exhaust valve spindle. The left half of the control chest is only partly shown, as it is constructed like the right hand half. 1 1

The live steam is admitted to the inlet 5, from which, as shown, the right admission valve 3 being open, it passes through the right channel 6 into the cylinder. The steam expended on the other piston side leaves the cylinder through a corresponding left passage 6 and is discharged through the outlet 1, the left exhaust valve 4 being opened.

In order to conduct the live steam from the inlet 5 also to the left piston side, a longitudinal channel 8 is provided in the control chest, extends to the left admission valve 3 and communicates with the left passage 6, when the admission valve 3 is open.

In similar manner the outflowing steam flows, when the right exhaust valve 4 is opened, from the front piston side to the outlet 1 through asecond longitudinal channel 9.

The longitudinal channels 8 and 9 may be omitted, in which case at each end of the control chest an inlet 5 and an outlet 1 are arranged.

The spindles of the distribution valves, constructed as double seat valves, are mounted in insert bushes I0 which are pressed into bores of the control chest 2. The spindles have labyrinth-grooves effecting the packing of the spindles towards the cam chambers. In the control chest two cam chambers II and I2 are provided in the form of construction illustrated, closed at the top by caps orcovers. The ends of the admission valve spindles I3 extend into chamber II, whereas the ends of the exhaust valve spindles I4 extend into the other chamber I2.

The control of the valves is effected from a shaft I5 journalled in the control chest 2 trans-. versely to the cylinder I and. driven in a suitable manner from a movable element of the locomotive. I

For controlling the admission valves 3, two cams E1 and E2 are mounted on the cam shaft I5 and can be mutually displaced by members mounted on the cams, for instance balls I8 and I8" placed in cavities of the cams which engage in grooves I9 of the cam shaft I5, so that the cams are moved into an adjusted position by a transverse movement of the rotating cam shaft I5.

A cradle 20, which is suspended at 2I on an intermediate lever 22, bears against the cylindrical circumference of the control cams E1 and E2. The intermediate lever 22 is oscillatably mounted in the control chest 2 on an axle 23, its free end bearing against the end of the admission valve spindle I3. A similar arrangement for the valve spindle is provided on the other side of the cam.

The cradle 20 is formed by two arms which are situated in different planes and curved in opposite directions so that the arm W 1 tangentially contacts on its entire width with the periphery of the cam E1 and the other arm W2 with the periphery of the cam E2.

For the control of the exhaust valves 4, the exhaust-cam A is loosely mounted on the cam shaft I5 and is coupled with this shaft in a similar manner by an element (ball). I9a engaging into the groove I9. A domed control face 21 of an intermediate lever 28 bears against the circumference of this cam, said intermediate lever being oscillatably mounted about an axle 29 in the control chest, the free end of saidintermediate lever acting upon the spindle ll of the exhaust valve. On the right-hand side of cam shaft I5 a similar intermediate lever is arranged for controlling the exhaust valve spindle I4.

Steam or air under pressure serves for closing the valves. With this object in view plungers 30 are mounted on the valves and adapted to pass through a bore of the actual valve chest cover 3|. Cylinders 32 are fixed on these covers and pistons 33,- shiftably mounted in these cylinders, bear against the plungers 30.

Every cylinder is connected'wlth the steam boiler or with a container for air under pressure by a pressure conduit not shown, so that the fluid under pressure can act upon the piston 33, when the conduit is opened, and moves the valves into the closing position.

This fluid under pressure serves at the same time to maintain the contact of the control elements for the admission valves during the expansion period. With this object in view a bolt I3a. is inserted into a bore 36 of the admission spindles I3, the head I3b of this bolt bearing against the end of the admission spindle I3 and the other side of the bolt head I3b bearing against the end of the intermediate lever 22. The space behind bolt I3a communicates through a bore 31 in the spindle I3 of the admission valve and in the plunger 30 with the pressure space 38 behind the piston 33. duced into space 38 can therefore permanently act upon the bolt I3a which, owing to the pressure exerted upon it, maintains the control elements 22, 20 in engagement with the cams.

For regulating the cut-off of the engine and also for reversing, the cam shaft I5 is mountedv shiftable. in axial direction, the adjusting of the admissionand exhaust-cams being effected by control grooves in the cam shaft which extend in accordance with the desired positions of the cam elements axially, partly helically as will be.

hereinafter explained.

In Figs. lato 7 it is supposed, that the cams are adjusted for maximum cut-off for forward running and that the cam shaft rotates in the direction of the arrow V and that further the piston is standing in the front end of its travel. During one and the same direction of travel the exhaust lead and the compression are not altered in the arrangement shown. The exhaust cam A, which controls the exhaust valves must therefore not turn relative to the cam shaft I5 during alteration of the cut-off. The part a of the groove I9 must therefore extend in the axial direction. If the direction of rotation is changed, the exhaust cam A must be adjusted from the medium position by the same angle in opposition for the new direction of movement. The part c of the control groove I9 for backward running must therefore be displaced from the dead point line m-:c by the same angle as part a of groove I9. To enable the transition from forward to backward running, ahelical transition groove 17 is provided, the length of which, measured in axial direction, corresponds to the reversing distance u.

The admission cams E1 andEz for controlling the admission valves are of such shape and posi- 7 tioned insuch a manner, that, if the one arm of the cradle 20 rests upon the base circle of the one cam, the other arm freely runs up on the second cam and lifts the intermediate lever 22 so far, that its end just touches the admission valve spindle, when the valve is closed, it being immaterial in which direction the cam shaft I rotates.

Fig. 5 shows the position of the control cams, in which the admission cams E1 and E2 are adjusted to maximum cut-off for forward running. The cam E2 has lifted the arm W2 of the cradle so far, that the end of the intermediate lever 22 just touches the spindle l3 of the admission valve 3. If the rotation of thecam shaft continues, the cam E1 begins to lift the arm W1 of the cradle whereby through the intermediate lever 22 the valve is lifted. This controlling edge of cam E1 determines therefor the admission lead. During further turning of the cam shaft the arms W1 and W2 of the cradle rest upon the corresponding extreme circumferences of the cams E1 and E2 which are concentrical to the axis (Fig. 6) whereby the admission valve -3 fully opens. If then the arm W2 of the cradleruns off the cam E2, the admission valve closes (Fig. '7) This running-off surface determines therefor the cut-off point. By adjusting of cam E2 the cutoff can be altered. The adjusting of the cam E2 is effected by a control groove 34 which at the .beginning has a helical branch 1 which determines different cut-offs according to the position of the cam shaft. During this adjusting the cam E1 is controlled by the axial groove 0, i. e. remains uninfluenced.

During the reversing of the direction of rotation of cam E2, which now determines the lead, must be maintained in its relative position to the cam shaft I5, whereas the cam E1 must be adjustable relative to the cam E2 for the purpose of regulating the cut-off. With this object in view, an axially directed branch 9 extends from the helical branch ,f' of. groove 34, whereas the cam E1 is adjusted by the helical part d of groove [9. This curve-part d extends from the axial curve part c which, during forward running, securely holds the admission cams and during backward running the. exhaust cam A.

' 19 if the control cam is accordingly constructed and ifsthe coupling elements are accordingly ar ranged, as is shown in Figs. 8 and 9. The portion d of the groove [9 coincides then with the portion f of groove 34.

During running forward and adjusted maximum cut-off the coupling element 18a for the exhaust cam A is at the beginning of groove a, the coupling element l8 for the cam Eris at the beginning of groove 0 and the coupling ele ment I8" for the cam E2 is at the end of groove 0. During the shifting of the cam shaft to theleft by the distance s1, the cams A and E1 remain in'their position, whereas the cam E2 is adjusted. During further shifting of the cam shaft by the The coupling element I311 is then at the beginning of the groove c, the coupling element l8 at. the beginning of groove (1, and the coupling element 48" at a. distance u from the beginning of the groove a. At further adjusting of the cam shaft by the distance 3r the exhaust cam A; and the admission cam E2 remain in the adjusted position, whereas the cam E1 is adjusted by the groove d and gives diflerent cut-offs. 9d show the different positions of the coupling elements for maximum and minimum cut-off forward and backward. t

The same kind of distribution may be employed also with such steam engines, in which the valves are arranged hanging in the cylinder. Fig. shows such an arrangementin section. In this instance two-armed bell crank levers 35 or 35a are substituted for the intermediate levers 22 or 28, the ends of the horizontal arms of these levers 35, 35a acting upon the valve spindles.

ate more or less from the axial directions as shown in Fig. 9e by the grooves a and c. In this manner, the compression can begin sooner and the exhaust lead later with larger cut-offs, that is lower running and lower counter-pressure.

The adaptation of the control points for the different cut-oifs may further be effected thereby, that the domed running-on face 21 for the exhaust cam A is arranged on an exchangeable shoe 24 which, by means of a pin 25, is mounted in the intermediate lever 28 or 35a (see Fig. 10). Then it is merely necessary to insert according to the desired displacement ofthe control points a control shoe of other shape.

The position of the control points may further be altered as the pivot axles of the. intermediate levers are made adjustable. A form of construction is shown by way of example in Fig. 11, which is a sectionon line XI-Xl of Fig. 10 on larger scale, showing an altered mounting ofthe bell crank lever 35. In this distance the pivot axle 39 of this bell crank lever-has pins 40 and 4| displaced eccentrically to the axle by the distance e, the pin 4| being cone-shaped and carrying a nut 42 for adjusting the pin 39, whereas the nut 43 serves for tightening the adjusted pin 39. The cradle 20 with the arms W1 and W2 is mounted on the upwardly directed arm of the bell crank lever 35 on a piv t pin 2 I.

A similar arrangement may also, as indicated in Fig. 7, be provided for the pivot axle of the intermediate levers 22 and 28. The axle 23 for the intermediate lever carries an eccentric pin 2311, by means of which the pivot axle can be adjusted higher or lower for altering the exhaust lead. During this adjustingalso the cut-off alters in a little measure. Toobtain the same cut-ofi as before it is merely necessary to make also the pivotaxle of cradle 20 adju'stable'about a pin 2la situated eccentric to it.

In Fig. 7 the same adjusting is indicated also for the exhaust intermediate lever 28 in that the Figs. 9a-

pivot axle 29 is equipped with an 'eccentrlca'lly arranged pin 29a. By the adjusting of the exhaust intermediate lever the beginning of the compression can then also be adjusted.

In order that during the axial shifting of the groove shaft no forces acting on one side occur and an easy guiding of the coupling elements in the control grooves is enabled, similar control grooves l9 and 19a are arranged in the cam shaft l5, said gooves extending diametrically the one to the other (Figs. 12-14) As coupling elements balls I8 can be employed as shown in Figs. 1 to 11 and engage in the guide grooves l9 and l9a.

Instead of balls, bolts 52 might be employed as shown in Figs. 12 and 13, the body 52' of these bolts being rotatably mounted directly in a bore of the cam body or in a bush 53 inserted in this bore. As in this instance the control grooves are produced by a circular milling cutter which corresponds approximately to the diameter of bolt 52, an accurate guiding in the control grooves is ensured thereby for coupling elements of this shape.

The coupling elements (balls or bolts) may further be inserted intoa separate coupling ring 51, as shown in Figs. 12 and 14. In this instance a ring 51 is pushed onto the cam shaft l5, said ring having for instance two diametrically opposite projections 58 which are bored, the bushes 53 and the coupling bolts 52 being mounted in said bores. In Fig. 14 this arrangement is shown on the exhaust control cam A. This cam has consequently a lateral recess 59, into which fit the claw-like extensions of the coupling ring so that, when the cam shaft l turns,'this ring rotates the cams. The coupling ring 51 need be inserted only loosely, as it is secured in its position by the spacing ring II.

In order to facilitate the production of the parts of the cam shaft which have the control grooves, they are made as separate parts l5 connected with the central part 15a of the cam shaft by coupling flanges N, Fig. 2. The cam shaft is rotated in any of the well known manners by a drive not illustrated.

The axial shifting of the cam shafts I5, I51; is similarly effected by mechanical arrangements of known type which are not shown as they do not form part of the invention. 7

During idle running of the engine all valves remain in the open position since the admission of pressure medium to the space 58 is shut off and this space has been brought into communication with the atmosphere.

-I claim:

1. Valve .gear for reversible, reciprocating fluid-pressure engines, especially for locomotives, comprising in combination an axially shiftable cam shaft, two admission and at least one exhaust control cam loosely mounted on said cam shaft and secured against lateral displacement, said cam shaft having in its circumference control grooves, coupling elements connected one to each of said control cams and engaging in 'said grooves, the pitches of the groove sections coordinated to each cam being different so that at the axial displacement of said cam shaft the individual cams are set independently through a different angle according to its function.

2. A valve gear as claimed in claim 1, in which the groove sections coordinated to the individual cams merge one into the other and form in the circumference of the cam shaft cam grooves extending in steps.

3. A valve gear as claimed in claim 1, in which the groove sections coordinated to the individual cams merge one into the other and form in the circumference of the cam shaft cam grooves extending in steps, the individual steps of the control grooves having different pitches.

4. A valve gear for reversible, reciprocating fluid-pressure engines, especially for locomotives, comprising in combination an axially shiftable cam shaft, two admission and at least one exhaust control cam loosely mounted on said cam shaft and secured against lateral displacement, intermediate members arranged between the ad- -mission cams and the spindles of the admission valves, rockers hingedly mounted on said members, arms on said rockers bearing against the two admission cams, .hollow admission valve spindles, pistons shiftable in said spindles pressed against said intermediate elements to ensure reliable contact of the control elements, said cam shaft having in its circumference control grooves, coupling elements connected one to each of said control cams and engaging in said grooves, the pitches of the groove sections coordinated to each cam being different so that at the axial displacement of said cam shaft the.individual cams are set independently through a different angle according to its function.

HUGO JOHANNES LENTZ. 

